[MachineFunction] Introduce a reset method.

This method allows to reset the state of a MachineFunction as if it was
just created. This will be used during the bring-up of GlobalISel to
provide a way to fallback on SelectionDAG. That way, we can start doing
correctness testing even if we are not able to select all functions via
the global instruction selector.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279876 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/MachineFunction.h b/include/llvm/CodeGen/MachineFunction.h
index ad72e84c07d..57b7bc6bf70 100644
--- a/include/llvm/CodeGen/MachineFunction.h
+++ b/include/llvm/CodeGen/MachineFunction.h
@@ -238,11 +238,28 @@ class MachineFunction {
 
   MachineFunction(const MachineFunction &) = delete;
   void operator=(const MachineFunction&) = delete;
+
+  /// Clear all the members of this MachineFunction, but the ones used
+  /// to initialize again the MachineFunction.
+  /// More specifically, this deallocates all the dynamically allocated
+  /// objects and get rid of all the XXXInfo data structure, but keep
+  /// unchanged the references to Fn, Target, MMI, and FunctionNumber.
+  void clear();
+  /// Allocate and initialize the different members.
+  /// In particular, the XXXInfo data structure.
+  /// \pre Fn, Target, MMI, and FunctionNumber are properly set.
+  void init();
 public:
   MachineFunction(const Function *Fn, const TargetMachine &TM,
                   unsigned FunctionNum, MachineModuleInfo &MMI);
   ~MachineFunction();
 
+  /// Reset the instance as if it was just created.
+  void reset() {
+    clear();
+    init();
+  }
+
   MachineModuleInfo &getMMI() const { return MMI; }
   MCContext &getContext() const { return Ctx; }